Treatment of animal tissue



June 20, 1944. c. T. WALTER TREATMENT OF ANIMAL TISSUE v Filed Feb. 9, y1942l Viuii -Patented June `20, 1944 UNITED STATES PATENT OFFICE TREATMENT F ANIMAL TISSUE v Charles T. Walter, Chicago, Ill., assignor to lndustrial Patents Corporation, Chicago, Ill., a corporation of Delaware Application February 9, 1942, Serial No. 430,170

17 Claims.

This invention relates to a process and apparatus for defatting animal tissue and more particularly to a process and apparatus in which a two stage process for separating fatty material from non-fatty material is carried out continuously so as to substantially completely defat the animal tissue. 4

In accordance with the present invention the more easily removed fat is separated in one stage and the more diiilcultly separated fat is removed in the second stage. By dividing the process into two stages the majority of the fat may be separated from the non-fatty material prior to a fine grinding operation thus reducingthe amount of material which must be subjected to such fine grinding operation. The animal tissue to be defatted is first subjected to a relatively coarse grinding operation which cuts the non-fatty material into pieces and scrapes a major portion of the' fat therefrom to form particles of fatty material. This relatively coarse mixture of particles of non-fatty material and particles of fatty material is subjected to a flotation process in a continuous manner to separate the fat particles from the other material. The non-fatty material which still has some fat adhering thereto is then subjected to ane grinding operation which cuts the non-fatty material into finer particles and at the same time scrapes substantially all of the remaining fat therefrom to form particles of fatty material. This resulting material is then subjected to a further flotation separation operation. It has been found that a substantial amount of fibrous material originally forming part of the fatty material and which separates with the non-fatty material if fine grinding and separation is attempted in a single operation, is removed from the non-fatty material and separated with the fatty material by the present invention. 'I'his brous material is deleterious in the non-fatty material.

The process also contemplates drying the nonfatty material to any desired water contentV by first draining this material and then subjecting it to agitation in a moving current of air. All of and the water discharged from the process being employed to carry the fat therefrom.

It has been found that the bottleneck in defatting operations of the general type above described has been the fine grinding operation and that the separation of mostof the fatty material strings of fibrous material that persist inthe nonfatty material when it is attempted to make the complete separation in a single step. Removal of such fibrous material is particularly important in producing a material suitable for gelatin manufacturing processes, as such fibrous tissues make it difficult to handle the material in gelatin manufacture and also prevent good drainage of the leaching solution from the non-fatty material during such gelatin manufacture.

It is, therefore, an object of the present invention to provide an improved process and apparatus for defatting animal tissue in which a two stage separation with a ne grinding operation intermediate the stages is employed.

Another object of the invention is to provide an improved process and apparatus for defatting animal tissue in which a first separation between relatively coarse particlesof f atty material and non-fatty material is effected by flotation and a nal separation between relatively fine particles the fatty material separated from the non-fatty of non-fatty material and fatty material is accomplished thereby decreasing the amount of material subjected to the fine grinding operation.

A further object of the invention is to provide a process and apparatus for defatting and drying animal tissues in which the non-fatty material in comminuted form is dried by a moving current of air while being agitated.

A still further object of the invention is to provide an improved process and apparatus for defatting animal tissue involving a two stage flotation separation in which water from the first ilotation stage carrying a small amount of fat is employed as a washing liquid and is discharged from the system as a carrier for fatty material.

Other objects and advantages of the invention will appear in the following description of a preferred embodiment of the invention made in connection with the attached drawing of which:

Fig. l is a diagrammatic view of apparatus suitable for carrying out the present invention;

Fig. 2 is a fragmentary view similar to Fig. l.

showing suitable mechanism for operating the fat discharge valve; and

Fig. 3 is a view similar to Fig. 2 showing the details of the mechanism Aof Fig. 2.

The apparatus for carrying out the present invention may include a conveyor I by which animal tissue 2 containing fatty and non-fatty -material is delivered to a rst hashing machine or grinder 3 .which may be of the type generally employed for grinding sausage or hamburger. The grinder 3 may be provided with a plate having relatively large openings for cutting the animal tissue into relatively large pieces and the material from the grinder'3 may be delivered into the hopper of a grinder 4 which may be provided with a plate having smaller holes for,

grinding the material into relatively coarse particles. Machines of the type described cut'the non-fatty material into particles and scrape at least a portion of the fatty material therefrom to form particles of fatty material. The @material from the grinder 4, consisting essentially of relatively coarse particles of fatty material superflcially adhering to relatively coarse particles of non-fatty'material, may be discharged into the `hopper 5 of an agitator 6 provided with a central shaft 1 rotated from any suitable source of power (not shown). The shaft 1 may have secured thereto a plurality of agitator blades 8 for separating and distributing the particles into water delivered into the hopper 5 through a pipe 9. The amount of water delivered into the hopper 5 may be controlled by a float. I0 and a float operated valve I I so as to maintain the agitator 6 full of material and a definite liquid level in the hopper 5. It will be apparent that the amount of water delivered into the hopper 5 will depend primarily upon the rate at which material is withdrawn from the agitator 6. The water containing the particles of animal tissue may be withdrawn from the agitator B and delivered by a pump I2 into an intermediate lportion of a separating chamber I3, preferably of cylindrical form and having an upper relatively steep conical portion I4 and a lower relatively steep conical portion I5. The upper conical portion I4 ymay terminate in a conduit I6 connecting the separation chamber I3 ,with a fat receiving chamber I1. The fat receiving chamber I1 may have a lower conical portion I8 connecting to the conduit I6 and a fat discharge conduit I9 may be connected to the conduit I6 between the separating chamber I3 and the fat receiving chamber I1.

A valve 22 may be provided for periodically closing and opening the end of the fat discharge conduit I9 so that the material in the fat receiving chamber may be Iperiodically discharged from the fat receiving chamber I1. For operating rthe valve 22 a float 23 may be secured to one arm of a 1ever33 pivoted at 34 on the casing of the fat collecting chamber I1 and having its other arm pivotally connected at 36 to one end of a link 31. The link 31 may have its other end pivotally connected to an arm 39 loosely journaled upon the shaft 4I of the valve 22. The shaft 4I may be supported in a bearing 42 secured to the casing of the separation chamber I3 and may have an arm 43 secured to its outer end. -A tension spring 44 may be connected between the end of the arm 43 and an extending member 45 carried by the end of the arm 39. It will be apparent that the spring 44 in the position of the floats shown holds the valve 22 in a position to open the conduit I9 and that flow of liquid out of the fat collecting chamber I1 will cause the float to drop thus pivoting the arm 39 about the shaft 4I until the spring 44 passes over the center of the shaft 4I whereupon the spring 44 will close the valve 22. Reverse operation will occur when the fat collecting chamber I1 again fills with liquid to raise the float 23'. The fatty material rises through the liquid in the separation chamber I3 and collects in the fat collecting chamber I1 along with water as hereafter described and is periodically discharged from the system through the conduit I9.

The non-fatty material sinks in the liquid in the separation chamber I3 and passes downwardly through the column of liquid in a relatively narrow lower extension 41 of the separation chamber I3. This non-fatty material collects in the lower portion of the extension 41 and is discharged therefrom along with a substantial portion of water through a suitable valve such as a star valve 4B driven from any suitable source of power (not shown). This non-fatty material is delivered into another hasher or grinding machine 49 provided with plates having relatively ne'holes so that the non-fatty material having only a small portiony of fat therein is subjected to the fine grinding operation. The particles from the fine grinding operation are delivered into the hopper 5I of a second agitator 52 which may be similar to the agitator 6 and be provided with a shaft 53 carrying a 'plurality of agitating blades 54. Water is also delivered into the hopper 5I through a pipe 56 provided with a valve 51 controlled by a float 58 in the hopper 5I so as to maintain the agitator 52 full of water and a substantially uniform liquid level in the hopper 5|.

'I'he relatively ner ground material is agitated with the water in the agitator 52 to liberate fat r from the non-fatty material and wash from the non-fatty material any film of fat adhering to the non-fatty material. It has been found that considerable fibrous material. originally forming part of the fatty material, adheres to and settles with the non-fatty material in the separation chamber I3. By again grinding this nonfatty material with very little fat present, it has further .been found that this fibrous material is substantially completely liberated from the non- \fatty material in the agitator 52. `The suspension of particles of animal tissue in water formed in the agitator is withdrawn by means of a pump 59 and delivered into an intermediate portion of a second separating chamber 6I -which is essentially similar to the separation cham-ber I3 and diiers therefrom primarily in that the upper end of the separation chamber 5I is closed except for communication with the lower portion of the lower extension 41 of the separation chamber I3 through a conduit 52.

Any fatty material liberated from the nonfatty material in the agitator 52 along with the fibrous material previously referred to rises through the liquid in the separation chamber 6I and is carried lby the pipe 52 into the lower por tion of the separation chamber I3. fatty material in the separating chamber 6I settles through the lower extension 53 of the separation chamber 6I and collects in the lower end thereof. This fatty material, which is sub- 'I'he nonstantially free of fat andxbrous material vfrom ter isdischarged from the separation chamber 6I through a suitable valve such as the star valve 64driven from any suitable source of power (not shown).

This mixture of non-fatty material and water is preferably delivered into one end of a drying drum 66 rotatable about a shaft '61 supported in bearings (not shown) and driven from a suitable source of power (also not shown). The entrance end 68 of the drum 66 is preferably provided with perforations 69 for draining a substantial amount of the water out of the non-fatty material received therein. This water collects in the pan 1I and is returned by means of pump 12 to the hopper 5I of the agitator 52. 66 may be provided with suitable baflles 13, shown in dotted lines, for tumbling or agitating the nonfatty material passing through the drum. The drum is preferably inclined downwardly towards its discharge end 14 so that the material being dried advances to the left in Fig. 1 and is discharged from the drum. Meanssuch as a fan 16 driven .by a motor 11 may be employed to direct a current of air through the drying drum 6-6 counter-current to the movement of the nonfatty material therethrough. It has been found that withthe combination of the moving current of air and the agitation of the non-fatty material moisture may be rapidly removed from' the non-fatty material to any extent desired even at relatively low temperatures.

Fresh water may be continuously introduced into the system through a pipe 18 connected to the lower portion of the extension 63 of separating chamber 6I. This fresh water is preferably The drying drum in the original fatty material. As the amount of fatty material and fibrous material separated from the non-fatty materialin the separating chamber 6I is small in amount relative to the fresh water introduced, the water owing through the pipe 62 can be efficiently employed to wash the non-fatty material settling in the lower extension 41 of the separating chamber I3. This water entering the separation chamber I3 displaces water from the first separation operation including the separation chamber I3 and the agitator 6, which displaced water rises in the fat collecting chamber I1 along with the fatty material and fibrous material separated from the non-fatty material in the separating chamber I3.

As Previously explained this displaced water is employed to intermittently flush the fatty material collecting in the fat collecting chamber I1 through the conduit I9 under control of the valve 22 and the float 23'.

It will thus be seen that a relatively small amount of water continuously flowing through a system containing a relatively large amount of water is employed for efficient washing operations and for discharging the fatty material from the system. The minimum amount of fresh water necessary is controlled primarily by the amount of water necessary to carry the fatty material out of the system and will dependupon the ratio introduced at substantially the temperature it is y to maintain vthis temperature substantially conf stant. The -water entering the system through the pipe ,18 flows upwardly through the lower extension 63 of the separation chamber 6I to wash the settling non-fatty material with fresh Water just prior to the discharge of the nonfatty material from the separating cham-ber. The amount of water introduced through the pipe 18 is not critical but should be sufficient to make4 up for water lost from the system in the drying operation in the drum 66 and also furnish the water employed to carry the` fatty material out of the system and prevent building up a fat and water emulsion in the system which might disturb the gravity balance therein so as to interfere with separation.

The fresh water displaces water from the'second stage of the operation including the separation chamber 6I and the agitator 52 and the displaced 'water flows from the separation chamber 6I through the pipe 62 into the lower portion of the extension 41 of the separation chamber I3. The water flowing through the pipe 62 carterial of low specific gravity of ythe type found The amount of water employed in the agitators 8 and 52 can be controlled independently by the pumps I2 and 59, respectively. The amount of water delivered to either agitator is independent of the amount of fresh water introduced into the system. The amount of water delivered to one of the Iagitatorsy for example the agitator 8, may vary within relatively wide limits. It should be enough to enable the particles of animal tissue to be separately suspendedl therein but. the

amount and rate of flow should not be great enough to cause undue turbulence in the separating chambers. It will be apparent that the amountl of water necessary will depend upon the throughput of animal tissue. This throughput of animal tissue is controlled primarily by the'rate of separation in the separating chambers and will vary with different types ofranimal tissue being treated.

In defatting pork skins the temperature maintained in the system is preferably approximately F. The higher the temperature employed the more easily the fat is separated from the nonfatty material as the higher temperatures soften the fat and make it more easily washed from the non-fatty material. On the other hand too high temperatures cook or coagulate the protein contentof the non-fatty material. In general, temperatures just below those at which the protein starts to coagulate are approximately the same as the temperatures at which the fat softens or partially melts. For materials which are more:` v

temperatures may be employed. In general, the lower the temperatures the less completely the fat is separated from the non-fatty material but in cases where only partial separation of the fat is desired much lower temperatures than that given can be employed. Thus temperatures ranging from slightly above the freezing point of water to temperatures approaching the coagulation temperature of the protein of the non-fatty material can be employed when it is desired to recover non-fatty material in which the protein content has not been modified. If coagulation of the protein is not deleterious for the purpose for which the non-fatty material is to be used, even higher temperatures approaching the boiling point of the liquid used may be employed.

While I have disclosed the preferred embodiment of my invention, it is understood that the details thereof may be varied within thescope of the following claims.

I claim:

l. The process of defatting animal tissue containing portions of fatty material and portions of non-fatty material, which comprises, hashing said animal tissue to form relatively coarse particles of fatty and non-fatty material, subjecting the hashed tissue to a flotationseparation step for separating particles of non-fatty material containing a small amount of fatty material from particles of fatty material, subjecting said particles of non-fatty material to a further hashing operation to form .relatively ne particles 'of hashed animal tissue, and subjecting said further hashed tissue to a further notation separation step for separating fatty material from said particles of non-fatty material.

2. The process cf defatting animal tissue containing portions of fatty material and portions of non-fatty material, which comprises, hashing said animal tissue into relatively coarse particles, suspending the hashed animal tissue in a liquid having a specific gravity intermediate the specic gravity of said fatty material and said nonfatty material, separating particles of non-fatty material containing a small amount of fatty` material from particles of fatty material by flotation in said liquid, subjecting the separated particles of non-fatty material to a further hashing operation to produce relatively fine particles, suspending said relatively fine particles in said liquid and again separating particles of non-fatty material from particles of fatty material by flotation in said liquid.

3.' The process as defined in claim 2 in which the separations are carried out in first and second separation zones, respectively, and in which a stream of said liquid is employed to carry fatty material from said second separation zone through said first separation zone and to discharge said fatty material from both said separation zones from said process.

4. The process as defined in claim 2 in which the first and second separations are carried out in first and second separation` zones, respectively, and in which a stream of fresh liquid is introduced into the-lower portion of said second separation zone for washing the non-fatty material settling therein and a stream of liquid displaced thereby from said second separation zone is employed to wash non-fatty material settling in saidfrst separation zone.

5. The process as defined in claim 2 in which the particles of non-fatty material from said second separation are dried by agitation in a moving current of air.

6. Apparatus for defatting animal tissue, which comprises, means for hashing said animal tissue into relatively coarse particles, an agitator for suspending said coarse particles in water, means for delivering, said particles and said water to said agitator, a first separating chamber containing a body of said water, means for delivering the suspension of particles of animal tissue and water formed in said agitator into an intermediate portion of said separation zone wherein said particles of non-fatty material settle through said liquid and the fatty material rises to the top of said liquid, a. second hashing means, means for withdrawing the separated particles of nonfatty material from said separating chamber and delivering same to said second hashing means, a second agitator for suspending said finer particles in water, means for delivering said finer particles and water into said second agitating means, a second separating chamber, means for delivering the suspension formed in said second agitator to said second separating chamber wherein said finer particles of non-fatty material settle in said second chamber and fatty material rises to the top of said second chamber, and means for removing defatted non-fatty material from said second chamber.

'7. An apparatus for defatting animal tissue, which comprises, a plurality of flotation separation chambers, means for hashing said animal tissue into relatively coarse particles, means for suspending said particles in water and delivering the same to a rst one of said separation c hambers wherein the relatively coarse particles of hashed animal material still containing a small amount of fatty material are separated from fatty material, means receiving said separated particles of non-fatty material from said first separating chamber and hashing the same into relatively fine particles, and means for suspending said relatively fine particles in water and delivering the same to a second separation chamber wherein said finer particles of non-fatty material are separated from said small amount of fatty material.

8. An apparatus forv defatting animal tissue,

which comprises, a plurality of flotation separation chambers, means for hashing said animal tissue into relatively coarse particles, means for suspending said particles in water and delivering the same to a first one of said separation chambers wherein the relatively coarse particles of hashed animal material still containing a small amount of fatty material are separated from fatty material, means receivingsaid separated' ing fatty material from the top of said second separating chamber and introducing the same into the lower portion of said first separation lchamber to wash non-fatty material settling therein, and means for discharging water carrying fatty material from the top of said first separating chamber.

9. Apparatus for defatting and drying animal tissue, which comprises, a hashing device for hashing said animal tissue into particles, agitating means for suspending said particles in water, a dotation chamber for separating particles of fatty material from particles of non-fatty material by difference in specific gravity in said water, adrying drum for receiving the particles of nonfatty material from said flotation chamber and agitating said last-named particles, and means for directing a current of air through said lastnamed particles during said agitation for'drying said last-named particles. l

10. The continuous process of defatting animal tissue containing portions of fatty material and portions of non-fatty material, which comprises, continuously hashing said animal tissue to form relatively coarse particlesof fatty and non-fatty material, subjecting the hashed tissue to a flotation separation step for separating particles of non-fatty material containing a small amount of fatty material from particles of fatty material, continuously subjecting said particles of non-fatty material to a further hashing operation to form relatively ne particles of hashed animal tissues, subjecting said further hashed tissue to a further flotation step for separating fatty material from said particles of non-fatty material, and continuously removing the fat separated from the non-fatty material during the flotation steps.

1l. An apparatus for defatting animal tissue, which comprises, a plurality of flotation separa tion chambers, means for hashing said animal tissue into relatively coarse particles, means for dispersing said coarsely hashed particles in a first one' of said Aseparation chambers wherein the relatively coarse particles of hashed animal material still containing a small amount of fatty material are separated from fatty material, means for receiving said separated particles of nonfatty material including hashing means for dividing the non-fatty material into relatively fine particles, and means for dispersingl said relatively fine particles in a second separation chamber wherein said finer particles of non-fatty material are substantially separated from said small amount of fatty material.

12. The process of defatting animal tissue containing portions of fatty material and portions of non-fatty material, which comprises, hashing said animal tissue to form relatively coarse particles of fatty and non-fatty material, subjecting the hashed tissue to a notation separation step for separating particles of non-fatty material containing a small amount of fatty material from particles of fatty material, subjecting said particles of said non-fatty material to a further hashing operation to form relatively fine particles of hashed animal tissue, subjecting said further hashed tissue to a further flotation separation step for separating fatty material from said particles of non-fatty material, adding` a flotation medium whereby to effect said flotation steps while controlling the quantity of medium added to an amount sufficient to continuously flush the system to prevent the accumulation of an emulsion between the medium and the fatty material which would destroy the specific gravity relationship prevailing in the flotation separating step.

13. The process of defatting animal tissue containing portions of fatty material and portions vof non-fatty material, which comprises, hashing said animal tissue to form relatively coarse particles of fatty andnon-fatty material, subjecting the hashed tissue to a flotation separation step for separating particles of non-fatty material containing a small amount of fatty material froml particles of fatty material, subjecting .said particles of non-fatty material to a further hashing operation to form relatively fine particles of hashed animal tissue, subjecting said further hashed tissue to a further flotation separation step for separating fatty material from said particles of non-fatty material, and heating said fatty material during at least one of said flotation separation steps to a temperature which tends to liquefy it.

14. The process of defatting animal tissue containing portions of fatty material and portions of non-fatty material, which comprises, hashing said animal tissue to form relatively coarse particles of fatty and non-fatty material, subjecting for separating particles ofv non-fatty material containing a small amount of fatty material from particles of fatty material, heating the fatty material to a temperature which tends toliquefy it, subjecting said particles of non-fatty material to a, further hashing operation to form relatively fine particles of hashed animal tissue, subjecting said,r further hashed tissue to a further notation separation step for separating fatty material from said particles of non-fatty material, and heating said fatty material during said further flotation separation step to a temperature which tends to liquefy it.

15. The process of defatting animal tissue containing portions of fatty material and protein matter, which comprises, hashing said animal tissue to form relatively coarse particles of fatty and protein material, subjecting the hashed tissue to a flotation separation step for separating particles of protein mattercontaining a small amount of fatty material from particles of fatty material, heating said fatty material during said separation, step to a temperature which tends to liquefy the fat while controlling the temperature to keep it below that temperature which will cook or coagulate the protein material, subject'- ing said protein matter to a further hashing operation to form relatively fine particles of hashed animal tissue, subjecting said further hashed tissue to a further fiotation separation step for separating fatty material from said ne particles of protein material, and heatingsaid fatty material during said further separation step to a temperature which tends to liquefy the fat while controlling the temperature to keep it below that temperature which will cook or coagulate the protein material.

16. 'I'he process of defatting animal tissue containing portions of fatty material and portions of non-fatty material, which comprises, hashing said animal tissue into relatively coarse particles, suspending the hashed animal tissue inl a liquid having a specific gravity intermediate the spciflc gravity of said fatty material and said nonfatty material, separating particles of non-fatty material containing a small amount of fatty material from particles of fatty material by A flotation in said liquid, subjecting the separated material from particles of fatty material by ilotation in said liquid, said separations being carried out in rst and second separation zones respectively, dispersing each of said hashed animal tissues in said liquid before delivering it into their respective separation zones, and drawing the dispersing liquid for each of the hashed animal tissues from the separation zone into which the hashed tissue is about to'ow.

17. A process of defatting animal tissue con taining portions of fatty material and protein matter, which comprises, hashing said animal tissue to form relatively coarse particles of fatty and protein material, subjecting the hushed tissue to a flotation separation step for separating is l0 to a temperature which tends to liquefy the fat while controlling the temperature to keep it,be low that temperature which will cook or coagula the protein material.

CHARLES T. WALTER. 

